Method of adjusting fuel injector valves



April 28, i959 s. G. wooDwARD Erm. 2,3%975 METHOD oF ADJUSTING FUELINJECTOR VALVES Filed Nov. 16, 1956 3 Sheets-Sheet 1 TTRN'Y April 28,1959 s. G. WOODWARD HAL 2,883,976

METHOD OF ADJUSTING FUEL INJECTOR VALVES Filed Nov. 16, 1956 3Sheets-Sheet, 2

@n TToRA/EY IN V ILV TORS Apri 28, w59 s. G. WQODWARD ETAL METHOD OF'ADJUSTING FUEL INJECTOR VALVES Filed Nov. 16 1955 mgm.

INVENTORS Unite States METHOD OF ADJUSTING FUEL INJECTOR VALVESApplication November 16, 1956, Serial No. 622,624

3 Claims. (Cl. 12S-119) The present invention relates generally to fuelinjection systems and more particularly to a method of adjusting theinjector valves of said system. US. application Serial No. 567,688 filedFebruary 24, 1956, in the names of Robert W. Sutton et al. assigned tothe assignee of the present invention and now abandoned, discloses andclaims a fuel injection system having solenoid actuated injector valvesto which thc method of adjustment of the present invention isparticularly applicable.

vlanulacturing variables introduce variations in the llowcharacteristics of the disclosed solenoid valve which must becompensated for by adjustment in order to obtain satisfactorydistribution in the fuel injection system. Adjustmcnt of the valve bypositioning an armature stop member in a predetermined position such asby the number'ot' turns of the stop member in a threaded retainer or byrelation to a reference point, has in practice, proved highlyunsatisfactory.

lt has been discovered that by applying a source of electrical energy tothe solenoid and measuring the current through the solenoid or voltageacross the solenoid that an abrupt change in current and voltage occursat the time the armature or valve engages the stop member. It wasfurther discovered that by adjusting the stop members of a plurality ofinjectors to obtain the same time duration from the time of applicationof the source of electrical energy to the time of the abrupt change incur rent or voltage that for equal energization of the solenoids equalfuel flow through the nozzles was obtained.

lt is accordingly an object of the invention to provide a simple,accurate method for adjusting electrically actuated valves to obtainuniform operation.

lt is a further object of the invention to provide a method foradjusting electrically actuated fuel injector valves which permits thevalves to be adjusted in their normally operative installed position.

Other objects and advantages will be readily apparent t rom thefollowing detailed description taken in connection with the appendeddrawings in which:

Figure l is a schematic view of a fuel injection system;

Figure 2 is a sectional View of an injector valve;

Figure 3 is n graph displaying a characteristic operating curve ol thesolenoid valve; and

Figure 4 is a schematic view of the circuitry of the electronic controlbox shown in Figure 1.

Referring now to thc drawings and more particularly to Figure l, numeraldesignates a fuel tank, 12 a pump mounted for dcliverying fuel receivedfrom the tank through a strainer or lter 14 to a fuel injector valve 16via conduit 18. Injector 16 is mounted in the induction passage 20 of amulti-cylinder internal combustion engine to inject fuel adjacent theinlet valve 22. The engine is shown fragntentarily and includes acombustion chamber 24 with a piston 26 mounted therein and a spark plug28 mounted thereon.

Pump l2 is adapted to deliver fuel at a controlled conslant or variablepressure to injector 16. The injector valve 16 is opened for a period oftime depending upon 2,883,976 Patented Apr. 23, 1959 a control, to bedescribed, whereby the quantity of fuel injected into the inductionpassage 20 varies as a function of time duration of valve opening andthe pressure of fuel supplied to the injector. Excess fuel supplied tothe injector 16 is returned to the fuel tank through conduit 30 andrestriction 32.

The control for the injector 16 includes throttle body assembly 3d,electronic control 36 and trigger-distributor 38. In operation, thetrigger-distributor 38 triggers or energizes the electronic control 36periodicalhl as a function of engine speed. Upon energization, theelectronic control 36 produces a pulse of electrical energy the width ortime duration of which is dependent upon various conditions which effectengine operation. Engine operating conditions are sensed by variouselements in the throttle body assembly 34 and are supplied to theelectronic control by appropriate conductors. The `output of theelectronic control 36 is connected to injector distributor 38 wherebythe pulse of electrical energy is connected to the appropriate solenoidin the circuit in accordance with the tiring order of the associatedengine. The solenoid in the injector valve 16 remains energized for aperiod of time dependent upon the width of the electrical pulse.

The throttle body assembly 34 includes a throttle body 40, inductionpassages 42 and 44 with throttle valves 46 and 4S respectively mountedtherein on a shaft 50. A throttle lever 52 is secured to shaft 50 and isadapted for actuation by a conventional accelerator pedal 54 through arod S6. A temperature control 58 is mounted on one side of the throttlebody and is connected through a link 60 with a fast idle cam 62 which ismounted for engagement with the throttle lever 52 to oppose the closingof the throttle when the control 58 is cold. Also mounted on body 10 isa vacuum responsive element 64 which is adapted to actuate a variableresistor or potentiometer 66. The latter being connected throughappropriate lead 68 to a switch 70 mounted on the body 40 for actuationby throttle shaft 50. Switch 70 is connected by lead 72 to theelectronic control 36. Ambient temperature responsive element 7d,atmospheric pressure responsive element 76 and engine temperatureresponsive element 70 are connected by appropriate leads to theelectronic control 36. An acceleration control 80 responsive to thepressure in the induction passage and containing a resistor 82 isconnected by appropriate leads to the control 36.

Referring now to Figure 4 wherein the circuit of the electronic controlis shown schematically'. Numeral 84 designates a triggering switch, 88 adistributor and 90 a plurality of solenoids, one for each of theinjector valves 16.

A lead 92 is provided to connect the control 36 through a switch 9-lwith a source of energy E. The energy source E may be a battery, magnetoor alternator conventionally associated with the engine to which thefuel injection system is connected. Likewise, the switch 94 may be theconventional ignition switch for such an engine.

The triggering device or switch 84 is connected by lead 88 to thecontrol 36 and by lead 100 to ground. Triggering switch 84 is mounted ona shaft 102 for actuation as a function of engine speed; and whenactuated produces a series of pulses in lead 104 substantially as shown.Each of these pulses is subsequently transformed into a pair of negativeand positive voltage spikes by a condenser 106. A rectifier 108connected to condenser 106 passes the negative spikes only to the base110 of a normallyI non-conducting transistor 112 of a monostablemulti-vibrator designated generally at 114. The collector 116 oftransistor 112 is connected to the base 118 of a normally conductingtransistor 120 through lead 122 and condenser C. When the negativevoltage spike is applied asesora to base 110, transistor 112 commencesto conduct whereby the potential in lead .122 is increased sufficientlyto drive transistor 120 into a non-conductive state. The time thattransistor 120 remains non-conductive is determined as a function of thevoltage decay rate of condenser C which in turn is controlled by thevalue of certain resistors, to be described, which collect condenser Cto ground.

ln the circuit of my invention, condenser C is connected to groundthrough alternative paths. The first of these paths comprises lead 124,variable resistors or potentiometers 126, 128, 66 and 82 or shunt 1311,lead 132, lead 63, switch 7G, variable resistors 132 and 1li-i andconductor 136 which is connected to ground or a reference potential.Resistor 126 is varied by element 76 as a function of change ofatmospheric pressure, resistor 12S is varied manually, resistor 66 isvaried by element 6-'1 as a function of change of induction passagepressure, resistor 82 and shunt 130 are controlled by accelerationdevice 80. resistor 132 is varied by element 74 as a function of changeof atmospheric or ambient temperature and resistor 134 is varied bvelement 78 as a function of change in engine temperature. The resistors126, 123, 66, 82, 132 and 13-3 are collectively designated as R1.

The second of the paths connecting condenser C to ground comprises lead12d, variable resistors 126 and 128, lead 72 and variable resistor 138.switch 711, variable resistors 132 and 134, and lead 140 which isconnected to ground or a reference potential. esistor 138 is variedmanually. Switch 70 is operatively connected to the engine throttlevalve and is arranged to close the second path above described when thethrottle is closed to a predetermined positiont Resistors 1215, 123,138, 132. 134 are collectively designated R2.

1n the operation of the multi-vibrator 11-'1 the negative voltage spiketriggers transistor 112 into conduction whereupon transistor 120 isdriven into a non-conductive state. Transistor 1213 remainsnon-conductive until the voltage on condenser C has decayed to a certainvalue. When the voltage on condenser C as applied to base 1.18 reaches apredetermined value transistor 12) becomes conductive and transistor 112is rendered non-conductive. Transistor il?, remains non-conductive untilretriggered by a negative voltage spike.

The action of the multi-vibrator produces a pulse in output lead 142 thewidth of which is controlled as a function of the time constant RIC orRZC depending upon the position of switch 79. The amplitude of the pulsein lead 142 varies from the normaly conducting voltage El tosubstantially zero. The output of the multi-vibrator 114 is coupled to apower amplifier designated generally at l-i--i hrough lead 142.condenser 148 and lead 150. /t diode 152 clamps lead 150 to lead 92 toinsure a substantially constant steady state voltage Ein lead 151) withreference to the voltage in lead 92. A pulse in lead 1&2 produces apulse in lead 151i of substantially the same width as the pulse in 142.The amplitude of the pulse in 150 varies from tlc reference voltage E toa lower voltage E2.

The puise in lead 150 causes transistor 154 in amplier l-i-i to conduct.The time that transistor -5 conducts is determined by the width ot" thepulse in lead 151) 'which in turn is determined as a function of thetime constant RC or REC. The output of transistor 154 is amplified bycascaded transistors 158 and 16u. The output of the amplifier sectionl-i-'l is connected by lead 162 to a cornmutator ring 16d in distributor88. A wiper arm 166 mounted on shaft 102 successively connects ring 154to contact segments 163. The contacts 168 are respectively connected tosolenoids 90 in the injector valves 16. The connections between contacts168 and solcnoids 16 are arranged so that successive engagement of thearm 166 with contacts 1153 cnergizes the solenoids in accordance withthe tiring order ofthe engine on which the solenoids are installed.

The injector 16 as best shown ln Figure 2 comprises a body 170 with anatrial conduit 172 passing therethrough. A metering restriction 174ithreadedly received in the discharge end of conduit 172 provides a seatfor a plastic 0r rubber like valve 176 which is secured to a piston orarmature 178 for reciprocation in conduit 172. Piston 178 is constructedof magnetizable material and is formed with a plurality of peripherallydisposed axial grooves 180 of such size as to permit the free passage offuel around the piston. A cylindrical abutment or stop member 182 isthreadedly received in conduit 172 upstream of piston 178 and isprovided with an axial bore 1&4 and at the lower end is provided with aplurality of slots 186 of such size as to permit the substantiallynon-rcstricted ow of fuel through member 182. A spring 183 is disposedbetween stop member 182 and piston 173 to urge them into a normallyspaced relation. Solenoid 90 is located in body 179 in a manner tosurround at least a portion of the stop member 182 and piston orarmature 178. Upon energization of the solenoid 90 by a pulse ofelectrical energy the piston 173 is moved into engagement with stopmember 182 and held there for the time duration of the application ofthe pulse of electrical energy. Adjustment of the stop member 182 for agiven electrical pulse and a given fuel pressure will vary the quantityof fuel discharged by the injector. Bccause of manufacturing tolerances,differences in materials, etc. it is ditlicult or impossible to produceinjectors in quantity that will have exactly thc same tiowcharacteristics for a given electrical pulse and fuel pressure. Becauseof the variation in the injectors it is difficult or impossible toadjust thc stop members to compensate lor these variations by indexingthe stop member a certain number of turns or positioning it in relationto a predetermined reference point. For some time the only method ofadjusting the valve was by trial and error which required removing theinjector from its operative position, removing the fuel connection,changing the position of the stop member, reconnecting the fuel hose andthen measuring the quantity ot` fuel discharged This trial and errormethod would have to be repeated a number of times for each injectorvalve.

1n Figure 3 there is shown a graph of the current in the voltage acrossthe solenoid 90 plotted against time. Figure 3 is representative of whatmight be seen on an oscilloscope connected to a solenoid 9) andtriggered by the same pulse of electrical energy applied to thesolenoid. As noted in Figure 3 current and voltage increase and decreaserespectively smoothly until time T has elapsed at which time an abruptchange occurs. This abrupt change occurs at the time that piston 178engages stop member 132. By adjusting the stop members 182 in each ofthe injector valves 16 so as to produce the same valve opening time Tfrom the time of the application of the pulse of electrical energy tothe time of abrupt change in current or voltage then for a given pulseof electrical energy and for a given fuel pressure the injectors willdischarge substantiaily the same quantity of fuel.

We claim:

1. The method of adjusting a plurality of solenoid actuated fuelinjectors having a stop member and an armature so as to provide forequal distribution of fuel to the cylinders of a multi-cylinder internalcombustion engine comprising the steps of applying a source ofelectrical energy to said solenoids, adjusting the stop member of one ofsaid injectors to produce a desired fuel flow, measuring the currenttiow in the solenoid of said one injector, measuring the time durationfrom the application of said source to the occurrence of a marked changein current in the solenoid of said one injector, and adjusting the stopmembers in the remaining injectors to obtain in the remaining solenoidssubstantially the same time duration from the application of said sourceto the occurrence of a marked change in current as the time duration inthe solenoid of said one injector.

asesora 2. The method of adjusting a solenoid actuated fuel valve havinga stop member and an armature comprising the steps of applying a sourceof electrical energy to said solenoid, measuring the current ow in thesolenoid, measuring the time duration from the application of saidsource to the occurrence of a marked change in current ow in saidsolenoid, and adjusting said stop member to provide a predetermined timeinterval between the application of said source and said marked changein current flow.

'3. The method of adjusting a solenoid actuated fuel valve having a stopmember and an armature so as io calibrate said valve to a referencecondition comprising the steps of applying a source of electrical energyto said solenoid, measuring the current ow in said solenoid, andadjusting said stop member to obtain a reference time duration from theapplication of said source o the occurrence of a marked change incurrent ow in said' solenoid.

Reierencea Ciied in the le of this patent UNITED STATES 'PATENTS1,268,913 Bair et al June 11, 1918 1,892,917 Walker et al 1an. 3, i9332,619,116 Ramon Nov. 25, 1952

